TopBand: Shunt feed responses

[John - G3XRJ -]

> Now, for my own chincy tower---
> Am I wasting my time trying to shunt feed 4 sections of Rohn 25 with a TH3
> at 42'? Would I be better off in the small lot with an inverted L or stick
> with my 80 meter horiz. loop with the ladder line shunted for 160 use (which
> doesnt hear DX very well) and put lots of raials underneath it?
      > Henry Heidtmann, N4VHK

 
Dont give up on it Henry.
I use a 3 section 37.5 ft 14inch triangular mast guyed at the top of second section
with 3 guys insulated at 20ft from top end. Top loading is 3 el tribander on 14 ft boom
on stub raised 1 ft above lattice top and stub extends 3 ft above boom so total height
is 41.5 ft.

Shunt feed is from top of lattice mast, 5 ft out and down to 1.5 ft above ground and 
into mast tuner box. Omega match is :- Series C = 100pf and Shunt C = 190pf.
Shunt C is coax and requires 2 inch pullback of braid at open end to prevent flashover.
The bandwidth is only 15khz between 2:1 points and only 5pf change of series C 
shifts 1:1 point about 15khz !.

Given its low theoretical efficiency , it works great. 
ZL short and longpath, JA, KH6 and KL7. 
ZL Long path is easy from G but the others are all a challenge.     

73's 
John G3XRJ


 
  

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